<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    // let n = +prompt('请输入循环次数')
    // let i = 1
    // while(i <= n){
    //   document.write(`杜哥真帅*${i}</br>`)
    //   i++
    // }
    let a = '3'
    let b = '7'
    document.write(b * a)
  </script>
</body>
</html>